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Epidemiology

PDAs occur in ~1 in 2000 full-term neonates with a F:M of 2:1 7,8.

Clinical presentation

A large PDA classically gives a loud continuous machine-like murmur.

Pathology

The ductus is a necessity in utero but usually undergoes functional closure 48 hours after birth. Patency of the ductus may be isolated or associated with other cardiac anomalies. In some circumstances, it is necessary to prolong life in patients with severe structural heart disease in whom a normal systemic circulation would be incompatible with life:

Non-cardiac associations

Radiographic features

Plain radiograph

Chest radiographic features may vary depending on whether it is isolated or associated with other cardiac anomalies and with the direction of shunt flow (right to left or left to right). Can have cardiomegaly (predominantly left atrial and left ventricular enlargement if not complicated). Obscuration of the aortopulmonary window and features of pulmonary edema may be evident.

Echocardiography

Transesophageal and transthoracic echocardiography have been used to identify these lesions, assess for the presence of complications, and plan surgical intervention. Suspicion is often aroused when a measured shunt fraction (Qp:Qs) is > 1.0, consistent with a left-to-right shunt.

With transthoracic echocardiography, the parasternal short axis view at the level of the aortic valve with color flow Doppler allows visualization of the flow through a patent ductus arteriosus. It classically appears as a high-velocity jet directed from the far-field toward the main pulmonary artery. Continuous wave Doppler interrogation reveals continuous flow throughout systole and diastole. Larger lesions, especially with concomitant pulmonary hypertension, may demonstrate lower flow velocities and/or alternating flow direction.

The suprasternal notch view may also depict aliased, continuous flow from the proximal descending aorta toward the right pulmonary artery, visible under the aortic arch in short-axis.

type B: window, short and wide ductus with blending of pulmonary artery

type C: long tubular ductus with no constrictions

type D: multiple constrictions with complex ductus

type E: elongated ductus with remote constriction

A ductus may have a tortuous morphology that does not fit in the Krichenko classification. This ductus type is usually observed in premature children and some authors proposed to classify it as type F or fetal type. Compared to types A to E, a type F ductus is larger, longer, tapers minimally from the aortic to pulmonary end, with a tortuous connection to the pulmonary artery giving a hockey-stick appearance 9.

Related Radiopaedia articles

Congenital heart disease

There is more than one way to present the variety of congenital heart diseases. Whichever way they are categorized, it is helpful to have a working understanding of normal and fetal circulation, as well as an understanding of the segmental approach to imaging in congenital heart disease.